A self-organized two-dimensional bimolecular structure

The production of a novel two-dimensional bimolecular surface structure using weak noncovalent interactions is demonstrated and observed by scanning tunneling microscopy (STM). This work follows closely the three-dimensional ideas of crystal engineering and applies the concepts of supramolecular synthons to molecular systems constrained to two dimensions by physisorption on a conducting surface. We demonstrate a well-ordered planar structure that self-assembles through the influence of fluorine-phenyl interactions. This study provides a concrete example of the systematic design of self-organized layers. Fully fluorinated cobalt phthalocyanine F16CoPc thermally deposited onto gold is characterized by RAIRS, XPS, and STM. UPS spectra of thin films of CoPc, F16CoPc. and nickel tetraphenylporphyrin (NiTPP) on gold are reported and their relative surface charges are compared. STM images of single molecular layers of F16CoPc, NiTPR and mixtures of NiTPP with F16CoPc and of NiTPP with CoPc are also presented. While NiTPP/F16CoPc spontaneously forms a well-ordered 1:1 structure, NiTPP/CoPc forms a two-dimensional solid solution.